1. Field of the Invention
The present invention relates to an acceleration plethysmograph, which can detect acceleration of a change in the contained-blood volume of a finger-apex, which is greatest in contained-blood volume and easily detected.
2. Description of the Prior Art
In the past, the functional examination of circulatory organs has been relied upon an electrocardiogram and blood pressure. However, apart from the blood pressure, opinion is divided on the electrocardiogram in interpretation thereof and problems are involved, which is therefore difficult to understand. Also, the electrocardiogram, for example, such as an exercise electrocardiogram, can detect a change in function in a special case, and a given organic change possibly appears, but it cannot judge the quality of circulation to assist in the prevention of future disease and to provide data necessary to recover the function.
Recent cases indicate that a person who does not always suffer high blood pressure is very often subject to infarction or subarachnoidal hemorrhage, and the mutual relationship therebetween is unkown, and accordingly, there is a demand of a new examination means.
On the other hand, a plethysmograph has been used as one of examination means of the circulatory function. That is, the pulse wave indicative of an increase or decrease in volume of blood within a capillary blood vessel is mechanically or electrically obtained as a fluctuation. A sensor for a plethysmograph measures a change in physical volume of fingers or the like, a change in impedance and a change in light permeability. The parts used for detection may include not only peripheral organs but various parts of the body. Clinically speaking, the peripheral blood stream is checked to thereby use it for examination of an abnormality of the aortic valve, the degree of arteriosclerosis, propagation time, the effect of a blood vessel expanding agent, the adjustment of vascular exercise, the indication of toxic symptoms resulting from the presence of poisonous matter within the body of a woman during pregnancy. This known method however is unreliable because it can be affected by temperature, tension of mind, drugs, respiration, etc. and in addition, a delusion in judgement may occur due to the obscurity of shape of the plethysmogram. For this reason, other examinations had to be referred to while reserving judgement resulting from said method. This method therefore is rarely utilized in plethysmography these days, and a plethysmograph is merely used as a heart beat signal of a heart beat meter.